package com.jeeww.lucene.demo;

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE
 * file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file
 * to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the
 * License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by
 * applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language
 * governing permissions and limitations under the License.
 */

import org.apache.lucene.analysis.Analyzer;
import org.apache.lucene.analysis.standard.StandardAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.document.LongField;
import org.apache.lucene.document.StringField;
import org.apache.lucene.document.TextField;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig.OpenMode;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.Term;
import org.apache.lucene.store.Directory;
import org.apache.lucene.store.FSDirectory;
import org.apache.lucene.util.Version;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.Date;

/**
 * Index all text files under a directory.
 * <p>
 * This is a command-line application demonstrating simple Lucene indexing. Run it with no command-line arguments for
 * usage information.
 */
public class IndexFiles {

    private IndexFiles() {
    }

    /** Index all text files under a directory. */
    public static void main(String[] args) {
        String indexPath = "d://test//index//";
        String docsPath = "d://test//docs//";
        boolean create = true;
        final File docDir = new File(docsPath);
        if (!docDir.exists() || !docDir.canRead()) {
            System.out.println("Document directory '" + docDir.getAbsolutePath()
                    + "' does not exist or is not readable, please check the path");
            System.exit(1);
        }

        Date start = new Date();
        try {
            System.out.println("Indexing to directory '" + indexPath + "'...");
            Directory dir = FSDirectory.open(new File(indexPath));
            // :Post-Release-Update-Version.LUCENE_XY:
            Analyzer analyzer = new StandardAnalyzer(Version.LUCENE_48);
            IndexWriterConfig iwc = new IndexWriterConfig(Version.LUCENE_48, analyzer);

            if (create) {
                // Create a new index in the directory, removing any
                // previously indexed documents:
                iwc.setOpenMode(OpenMode.CREATE);
            } else {
                // Add new documents to an existing index:
                iwc.setOpenMode(OpenMode.CREATE_OR_APPEND);
            }

            // Optional: for better indexing performance, if you
            // are indexing many documents, increase the RAM
            // buffer. But if you do this, increase the max heap
            // size to the JVM (eg add -Xmx512m or -Xmx1g):
            //
            // iwc.setRAMBufferSizeMB(256.0);

            IndexWriter writer = new IndexWriter(dir, iwc);
            indexDocs(writer, docDir);

            // NOTE: if you want to maximize search performance,
            // you can optionally call forceMerge here. This can be
            // a terribly costly operation, so generally it's only
            // worth it when your index is relatively static (ie
            // you're done adding documents to it):
            //
            // writer.forceMerge(1);

            writer.close();

            Date end = new Date();
            System.out.println(end.getTime() - start.getTime() + " total milliseconds");
            
        } catch (IOException e) {
            System.out.println(" caught a " + e.getClass() + "\n with message: " + e.getMessage());
        }
    }

    /**
     * Indexes the given file using the given writer, or if a directory is given, recurses over files and directories
     * found under the given directory. NOTE: This method indexes one document per input file. This is slow. For good
     * throughput, put multiple documents into your input file(s). An example of this is in the benchmark module, which
     * can create "line doc" files, one document per line, using the <a
     * href="../../../../../contrib-benchmark/org/apache/lucene/benchmark/byTask/tasks/WriteLineDocTask.html"
     * >WriteLineDocTask</a>.
     * @param writer Writer to the index where the given file/dir info will be stored
     * @param file The file to index, or the directory to recurse into to find files to index
     * @throws IOException If there is a low-level I/O error
     */
    static void indexDocs(IndexWriter writer, File file) throws IOException {
        // do not try to index files that cannot be read
        if (file.canRead()) {
            if (file.isDirectory()) {
                String[] files = file.list();
                // an IO error could occur
                if (files != null) {
                    for (int i = 0; i < files.length; i++) {
                        indexDocs(writer, new File(file, files[i]));
                    }
                }
            } else {

                FileInputStream fis;
                try {
                    fis = new FileInputStream(file);
                } catch (FileNotFoundException fnfe) {
                    // at least on windows, some temporary files raise this exception with an "access denied" message
                    // checking if the file can be read doesn't help
                    return;
                }

                try {

                    // make a new, empty document
                    Document doc = new Document();

                    // Add the path of the file as a field named "path". Use a
                    // field that is indexed (i.e. searchable), but don't tokenize
                    // the field into separate words and don't index term frequency
                    // or positional information:
                    Field pathField = new StringField("path", file.getPath(), Field.Store.YES);
                    doc.add(pathField);

                    // Add the last modified date of the file a field named "modified".
                    // Use a LongField that is indexed (i.e. efficiently filterable with
                    // NumericRangeFilter). This indexes to milli-second resolution, which
                    // is often too fine. You could instead create a number based on
                    // year/month/day/hour/minutes/seconds, down the resolution you require.
                    // For example the long value 2011021714 would mean
                    // February 17, 2011, 2-3 PM.
                    doc.add(new LongField("modified", file.lastModified(), Field.Store.NO));

                    // Add the contents of the file to a field named "contents". Specify a Reader,
                    // so that the text of the file is tokenized and indexed, but not stored.
                    // Note that FileReader expects the file to be in UTF-8 encoding.
                    // If that's not the case searching for special characters will fail.
                    doc.add(new TextField("contents", new BufferedReader(new InputStreamReader(fis,
                            StandardCharsets.UTF_8))));

                    if (writer.getConfig().getOpenMode() == OpenMode.CREATE) {
                        // New index, so we just add the document (no old document can be there):
                        System.out.println("adding " + file);
                        writer.addDocument(doc);
                    } else {
                        // Existing index (an old copy of this document may have been indexed) so
                        // we use updateDocument instead to replace the old one matching the exact
                        // path, if present:
                        System.out.println("updating " + file);
                        writer.updateDocument(new Term("path", file.getPath()), doc);
                    }

                } finally {
                    fis.close();
                }
            }
        }
    }
}
